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  Python函数
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  <h1 id="函数的使用"><a href="#函数的使用" class="headerlink" title="函数的使用"></a>函数的使用</h1><p>函数，在数学中就有封装的概念了</p>
<p>数学中的函数可以看作一个公式，一个用来计算多个数据的公式，用来处理重复的运算</p>
<p>编程中的函数可以看作一堆语句的结合，用来处理重复的动作(语句)</p>
<p>函数的使用包含了两个步骤： <strong>封装</strong> 和 <strong>调用</strong></p>
<ul>
<li><h2 id="自定义函数–封装"><a href="#自定义函数–封装" class="headerlink" title="自定义函数–封装"></a>自定义函数–封装</h2><p>  封装，把一些代码封装成一个个小的程序块，用于调用</p>
<p>  自定义函数的代码语法如下：</p>
  <figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">def</span> <span class="title function_">fac_name</span>(<span class="params">args1=<span class="string">&quot;1&quot;</span>,args2</span>):</span><br><span class="line"></span><br><span class="line">    <span class="built_in">print</span>(args1,args2)</span><br><span class="line"></span><br><span class="line">    <span class="keyword">pass</span></span><br><span class="line"></span><br><span class="line">    <span class="string">&quot;...&quot;</span></span><br></pre></td></tr></table></figure>

<p>  其中：</p>
<p>  <strong>def</strong> 是单词define的缩写代表 <strong>定义</strong></p>
<p>  <strong>fec_name</strong> 是你的定义的函数名，本质上属于 <strong>标识符</strong></p>
<p>  <strong>args</strong> 参数，带等号的就是有默认值的参数；不带等号的必须在调用时进行参数添加</p>
<p>  剩下的语句可以随意添加</p>
</li>
<li><h2 id="调用函数–调用"><a href="#调用函数–调用" class="headerlink" title="调用函数–调用"></a>调用函数–调用</h2><p>  调用自己定义的函数很简单</p>
<p>  实例如下:</p>
  <figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">def</span> <span class="title function_">show_99</span>(<span class="params">statue</span>):</span><br><span class="line">    <span class="keyword">if</span> statue == <span class="literal">True</span>:</span><br><span class="line">        <span class="keyword">for</span> a <span class="keyword">in</span> <span class="built_in">range</span>(<span class="number">1</span>,<span class="number">10</span>,<span class="number">1</span>):</span><br><span class="line">            b = <span class="number">1</span></span><br><span class="line">            line = <span class="string">&quot;&quot;</span></span><br><span class="line">            <span class="keyword">while</span> b &lt;= a :</span><br><span class="line">                line += (<span class="string">&quot;%d x %d = %d &quot;</span> %(b,a,a*b))</span><br><span class="line">                b += <span class="number">1</span></span><br><span class="line">            <span class="built_in">print</span>(line)</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">show_99(statue=<span class="number">1</span>)</span><br></pre></td></tr></table></figure>

<p>  要想调用一个函数，直接输入其函数名，再将必要的参数进行赋值 <em>(必要参数就是没有默认值的，如果参数都有默认值，不另外赋值也可)</em> 即可</p>
<p>  推荐在调用时单独给每个形参赋值</p>
<p>  <em><strong>特别注意：由于python解释器逐条解释的原因，必须将<code>调用</code>写在<code>定义</code>之后</strong></em></p>
<p>  <em><strong>另外，解释器为了防止识别错误，规定在定义函数时，有默认值的参数必须置于无默认值的参数之后</strong></em></p>
<p>  此外，定义时形参前加<code>*</code>表示多值参数(与拆包操作相同)</p>
<p>  <code>*data</code>表示元组</p>
<p>  <code>**data</code>表示字典</p>
</li>
<li><h2 id="函数的文档注释"><a href="#函数的文档注释" class="headerlink" title="函数的文档注释"></a>函数的文档注释</h2><p>  若想给函数添加注释，应在<code>def</code>的下一行添加一个多行注释即可</p>
<p>  <img src="/wdzs.png" alt="文档注释"></p>
<p>  <em><strong>tips：相对于其他语句，def的自定义函数快是一个相对独立的整体，应与其他非空行保持两行的间距</strong></em></p>
</li>
<li><h2 id="参数"><a href="#参数" class="headerlink" title="参数"></a>参数</h2>  <figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">def</span> <span class="title function_">show_99</span>(<span class="params">statue</span>):</span><br><span class="line">    <span class="keyword">if</span> statue == <span class="literal">True</span>:</span><br><span class="line">        <span class="keyword">for</span> a <span class="keyword">in</span> <span class="built_in">range</span>(<span class="number">1</span>,<span class="number">10</span>,<span class="number">1</span>):</span><br><span class="line">            b = <span class="number">1</span></span><br><span class="line">            line = <span class="string">&quot;&quot;</span></span><br><span class="line">            <span class="keyword">while</span> b &lt;= a :</span><br><span class="line">                line += (<span class="string">&quot;%d x %d = %d &quot;</span> %(b,a,a*b))</span><br><span class="line">                b += <span class="number">1</span></span><br><span class="line">            <span class="built_in">print</span>(line)</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">show_99(statue=<span class="number">1</span>)</span><br></pre></td></tr></table></figure>

<p>  还是刚才的实例，由此引出两个概念<strong>形参</strong>和<strong>实参</strong></p>
<ul>
<li><p>形参：<code>def show_99(statue):</code>里面的<code>statue</code>就是形参</p>
<p>  具体来说，形参就是<strong>定义函数</strong>时传递到函数内部的变量是形参</p>
</li>
<li><p>实参：<code>show_99(statue=1)</code>中的<code>statue=1</code>或者单独一个<code>1</code>就是实参</p>
<p>  实参就是参数在<strong>调用函数</strong>时的具体表现值(实际数据)</p>
</li>
</ul>
</li>
<li><h2 id="返回值"><a href="#返回值" class="headerlink" title="返回值"></a>返回值</h2><p>  返回值函数<code>return</code>可以返回你的结果，结果可以是在函数中所得的所有值</p>
<p>  return函数是一个输入函数(类似于input)所以这个函数不会将生成的值输出到控制台中，但可以将其值输入给其他函数</p>
<p>  实例：</p>
  <figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">def</span> <span class="title function_">test</span>():</span><br><span class="line"><span class="string">&quot;&quot;&quot;</span></span><br><span class="line"><span class="string">测试函数的文档注释</span></span><br><span class="line"><span class="string">&quot;&quot;&quot;</span></span><br><span class="line"><span class="keyword">return</span> <span class="string">&quot;nothing&quot;</span></span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(test())</span><br></pre></td></tr></table></figure>

<p>  这样<code>test()</code>就看做一个输入函数了</p>
<p>  <em><strong>注意：<code>return</code>关键字后的代码将不会被执行</strong></em></p>
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                    const image = new Image()
                    image.src = src
                    items.push({
                        src: src,
                        w: image.width || $em2.width,
                        h: image.height || $em2.height,
                        title: title
                    })
                })
                var gallery = new PhotoSwipe(pswpElement, PhotoSwipeUI_Default, items, {
                    index: parseInt(i)
                });
                gallery.init()
            }
        })
    }
    viewer_init()
</script> 
<!-- MathJax -->

<!-- Katex -->

<!-- busuanzi  -->
 
<script src="/js/busuanzi-2.3.pure.min.js"></script>
 
<!-- ClickLove -->

<!-- ClickBoom1 -->

<!-- ClickBoom2 -->

<!-- CodeCopy -->
 
<link rel="stylesheet" href="/css/clipboard.css">
 <script src="https://cdn.jsdelivr.net/npm/clipboard@2/dist/clipboard.min.js"></script>
<script>
  function wait(callback, seconds) {
    var timelag = null;
    timelag = window.setTimeout(callback, seconds);
  }
  !function (e, t, a) {
    var initCopyCode = function(){
      var copyHtml = '';
      copyHtml += '<button class="btn-copy" data-clipboard-snippet="">';
      copyHtml += '<i class="ri-file-copy-2-line"></i><span>COPY</span>';
      copyHtml += '</button>';
      $(".highlight .code pre").before(copyHtml);
      $(".article pre code").before(copyHtml);
      var clipboard = new ClipboardJS('.btn-copy', {
        target: function(trigger) {
          return trigger.nextElementSibling;
        }
      });
      clipboard.on('success', function(e) {
        let $btn = $(e.trigger);
        $btn.addClass('copied');
        let $icon = $($btn.find('i'));
        $icon.removeClass('ri-file-copy-2-line');
        $icon.addClass('ri-checkbox-circle-line');
        let $span = $($btn.find('span'));
        $span[0].innerText = 'COPIED';
        
        wait(function () { // 等待两秒钟后恢复
          $icon.removeClass('ri-checkbox-circle-line');
          $icon.addClass('ri-file-copy-2-line');
          $span[0].innerText = 'COPY';
        }, 2000);
      });
      clipboard.on('error', function(e) {
        e.clearSelection();
        let $btn = $(e.trigger);
        $btn.addClass('copy-failed');
        let $icon = $($btn.find('i'));
        $icon.removeClass('ri-file-copy-2-line');
        $icon.addClass('ri-time-line');
        let $span = $($btn.find('span'));
        $span[0].innerText = 'COPY FAILED';
        
        wait(function () { // 等待两秒钟后恢复
          $icon.removeClass('ri-time-line');
          $icon.addClass('ri-file-copy-2-line');
          $span[0].innerText = 'COPY';
        }, 2000);
      });
    }
    initCopyCode();
  }(window, document);
</script>
 
<!-- CanvasBackground -->
 
<script src="/js/dz.js"></script>
 
<script>
  if (window.mermaid) {
    mermaid.initialize({ theme: "forest" });
  }
</script>


    
    <div id="music">
    
    
    
    <iframe frameborder="no" border="1" marginwidth="0" marginheight="0" width="200" height="52"
        src="//music.163.com/outchain/player?type=2&id=1329665666&auto=0&height=32"></iframe>
</div>

<style>
    #music {
        position: fixed;
        right: 15px;
        bottom: 0;
        z-index: 998;
    }
</style>
    
    

  </div>
</body>

</html>